The present invention relates to a rock drill bit for rotary crushing machining of rock, including at least a leg carrying a bearing journal provided with bearing surfaces in order to cooperate with races via bearing elements in a thereby rotatable roller cutter equipped with a crushing organ, the leg comprising a tail and seal means intended to counteract entrance of drill cuttings into the bearings, the seal means furthermore being intended to retain bearing grease; the seal means being concentrically provided around the bearing journal and being intended to slide against the roller cutter.